The present invention relates to a disc drive slider piezoelectric engagement and microactuating device that can be manufactured by mass production fabrication techniques.
In disc drive applications, it is desirable to implement a slider with the capability to selectively adjust the position of a transducer or optical head in relation to the disc medium. This capability is utilized to load and unload the head over the disc medium, to disengage the head from the disc medium while flying over the disc, and to dynamically adjust the fly height of the head while reading and/or writing data to and from the disc medium.
One solution for on-demand engagement and disengagement of a head involves machining a slot in the proximal end of the slider carrying the head, and fastening a piezoelectric stack in the slot such as by an adhesive. Activating the piezoelectric stack causes the slider to bend, thereby engaging the head carried on the slider in proximity with the disc media. However, this solution is not suitable for mass production, making it prohibitively expensive and time consuming to manufacture in any substantial quantity.
In addition to the need for a selective engagement device, there is also a need for a high resolution microactuator to precisely position the head over a selected radial track of the disc. More particularly, as efforts continue to increase track density, the radial spacing between concentric data tracks on the disc decreases. Conventional actuator motors, such as voice coil motors, lack sufficient resolution to effectively accommodate high track-density discs, necessitating the addition of a high resolution head microactuator.
Various microactuator designs have been considered to accomplish high resolution head positioning, including piezoelectric, electromagnetic, electrostatic, capacitive, fluidic, and thermal actuators. Various locations for the microactuator have been suggested, including on the slider itself and at the head mounting block connecting the head suspension load beam to the actuator arm, for example. However, previous microactuator designs have several shortcomings which limit their effectiveness. For example, many previous microactuator designs were directed to microactuators fabricated independently of the slider which had to be subsequently attached to the slider. Consequently, the microactuator could not be fabricated during the same thin film wafer processing for manufacturing the slider and transducing head, and additional tooling and assembly steps were required to attach the microactuator to the slider. As a result, the complexity of the manufacturing process increased and additional fabrication steps, separate from existing manufacturing techniques, were required, making these microactuator designs prohibitively expensive and inefficient to produce. Also, previous microactuator designs which located the microactuator distant from the slider, such as at the head mounting block, could achieve only limited frequency response in micropositioning the head, due to the relatively large mass being moved by the microactuator motor. Other microactuator designs suffered from these and various other limitations.
There is a need in the art for a device to provide selective engagement and disengagement of a transducing head in proximity with a disc media, and also for a device providing high resolution radial head positioning over selected data tracks of a disc. More particularly, there is a need for each of these devices in designs that can be fabricated onto the slider using existing wafer processing techniques, enabling easy and inexpensive mass production.